diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 68a06b01dc..6649e491a6 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -230,15 +230,7 @@ sub new {
     $self->{right_panel} = Wx::ScrolledWindow->new($self, -1, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
     $self->{right_panel}->SetScrollbars(0, 1, 1, 1);
     
-    ### Scrolled Window for info boxes
-    my $scrolled_window_sizer = Wx::BoxSizer->new(wxVERTICAL);
-    $scrolled_window_sizer->SetMinSize([310, -1]);
-#    my $scrolled_window_panel = Wx::ScrolledWindow->new($self->{right_panel}, -1, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
-    my $scrolled_window_panel = Wx::Panel->new($self->{right_panel}, -1, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
-    $scrolled_window_panel->SetSizer($scrolled_window_sizer);
-#    $scrolled_window_panel->SetScrollbars(1, 1, 1, 1);    
-
-    $self->{list} = Wx::ListView->new($scrolled_window_panel, -1, wxDefaultPosition, wxDefaultSize,
+    $self->{list} = Wx::ListView->new($self->{right_panel}, -1, wxDefaultPosition, wxDefaultSize,
         wxLC_SINGLE_SEL | wxLC_REPORT | wxBORDER_SUNKEN | wxTAB_TRAVERSAL | wxWANTS_CHARS );
     $self->{list}->InsertColumn(0, L("Name"), wxLIST_FORMAT_LEFT, 145);
     $self->{list}->InsertColumn(1, L("Copies"), wxLIST_FORMAT_CENTER, 45);
@@ -424,7 +416,7 @@ sub new {
 
         my $object_info_sizer;
         {
-            my $box = Wx::StaticBox->new($scrolled_window_panel, -1, L("Info"));
+            my $box = Wx::StaticBox->new($self->{right_panel}, -1, L("Info"));
             $box->SetFont($Slic3r::GUI::small_bold_font);
             $object_info_sizer = Wx::StaticBoxSizer->new($box, wxVERTICAL);
             $object_info_sizer->SetMinSize([300,-1]);
@@ -443,14 +435,14 @@ sub new {
             );
             while (my $field = shift @info) {
                 my $label = shift @info;
-                my $text = Wx::StaticText->new($scrolled_window_panel, -1, "$label:", wxDefaultPosition, wxDefaultSize, wxALIGN_LEFT);
+                my $text = Wx::StaticText->new($self->{right_panel}, -1, "$label:", wxDefaultPosition, wxDefaultSize, wxALIGN_LEFT);
                 $text->SetFont($Slic3r::GUI::small_font);
                 $grid_sizer->Add($text, 0);
                 
-                $self->{"object_info_$field"} = Wx::StaticText->new($scrolled_window_panel, -1, "", wxDefaultPosition, wxDefaultSize, wxALIGN_LEFT);
+                $self->{"object_info_$field"} = Wx::StaticText->new($self->{right_panel}, -1, "", wxDefaultPosition, wxDefaultSize, wxALIGN_LEFT);
                 $self->{"object_info_$field"}->SetFont($Slic3r::GUI::small_font);
                 if ($field eq 'manifold') {
-                    $self->{object_info_manifold_warning_icon} = Wx::StaticBitmap->new($scrolled_window_panel, -1, Wx::Bitmap->new(Slic3r::var("error.png"), wxBITMAP_TYPE_PNG));
+                    $self->{object_info_manifold_warning_icon} = Wx::StaticBitmap->new($self->{right_panel}, -1, Wx::Bitmap->new(Slic3r::var("error.png"), wxBITMAP_TYPE_PNG));
                     #$self->{object_info_manifold_warning_icon}->Hide;
                     $self->{"object_info_manifold_warning_icon_show"} = sub {
                         if ($self->{object_info_manifold_warning_icon}->IsShown() != $_[0]) {
@@ -475,7 +467,7 @@ sub new {
 
         my $print_info_sizer;
         {
-            my $box = Wx::StaticBox->new($scrolled_window_panel, -1, L("Sliced Info"));
+            my $box = Wx::StaticBox->new($self->{right_panel}, -1, L("Sliced Info"));
             $box->SetFont($Slic3r::GUI::small_bold_font);
             $print_info_sizer = Wx::StaticBoxSizer->new($box, wxVERTICAL);
             $print_info_sizer->SetMinSize([300,-1]);
@@ -493,11 +485,11 @@ sub new {
             );
             while (my $field = shift @info) {
                 my $label = shift @info;
-                my $text = Wx::StaticText->new($scrolled_window_panel, -1, "$label:", wxDefaultPosition, wxDefaultSize, wxALIGN_RIGHT);
+                my $text = Wx::StaticText->new($self->{right_panel}, -1, "$label:", wxDefaultPosition, wxDefaultSize, wxALIGN_RIGHT);
                 $text->SetFont($Slic3r::GUI::small_font);
                 $grid_sizer->Add($text, 0);
                 
-                $self->{"print_info_$field"} = Wx::StaticText->new($scrolled_window_panel, -1, "", wxDefaultPosition, wxDefaultSize, wxALIGN_LEFT);
+                $self->{"print_info_$field"} = Wx::StaticText->new($self->{right_panel}, -1, "", wxDefaultPosition, wxDefaultSize, wxALIGN_LEFT);
                 $self->{"print_info_$field"}->SetFont($Slic3r::GUI::small_font);
                 $grid_sizer->Add($self->{"print_info_$field"}, 0);
             }
@@ -511,18 +503,22 @@ sub new {
         $buttons_sizer->Add($self->{btn_print}, 0, wxALIGN_RIGHT, 0);
         $buttons_sizer->Add($self->{btn_send_gcode}, 0, wxALIGN_RIGHT, 0);
         #$buttons_sizer->Add($self->{btn_export_gcode}, 0, wxALIGN_RIGHT, 0);
-        
-        $scrolled_window_sizer->Add($self->{list}, 1, wxEXPAND, 5);
-        $scrolled_window_sizer->Add($object_info_sizer, 0, wxEXPAND | wxLEFT, 20);
-        $scrolled_window_sizer->Add($print_info_sizer, 0, wxEXPAND | wxLEFT, 20);
+
+        ### Sizer for info boxes
+        my $info_sizer = Wx::BoxSizer->new(wxVERTICAL);
+        $info_sizer->SetMinSize([310, -1]);        
+        $info_sizer->Add($self->{list}, 1, wxEXPAND, 5);
+        $info_sizer->Add($object_info_sizer, 0, wxEXPAND | wxBOTTOM, 5);
+        $info_sizer->Add($print_info_sizer, 0, wxEXPAND | wxBOTTOM, 5);
 
         my $right_sizer = Wx::BoxSizer->new(wxVERTICAL);
+        $self->{right_panel}->SetSizer($right_sizer);
         $right_sizer->SetMinSize([320, -1]);
         $right_sizer->Add($presets, 0, wxEXPAND | wxTOP, 10) if defined $presets;
         $right_sizer->Add($frequently_changed_parameters_sizer, 1, wxEXPAND | wxTOP, 0) if defined $frequently_changed_parameters_sizer;
         $right_sizer->Add($expert_mode_part_sizer, 0, wxEXPAND | wxTOP, 0) if defined $expert_mode_part_sizer;
         $right_sizer->Add($buttons_sizer, 0, wxEXPAND | wxBOTTOM, 5);
-        $right_sizer->Add($scrolled_window_panel, 0, wxEXPAND | wxALL, 1);
+        $right_sizer->Add($info_sizer, 0, wxEXPAND | wxLEFT, 20);
         $right_sizer->Add($self->{btn_export_gcode}, 0, wxEXPAND | wxLEFT | wxTOP | wxBOTTOM, 20);
         # Callback for showing / hiding the print info box.
         $self->{"print_info_box_show"} = sub {
@@ -530,18 +526,16 @@ sub new {
 #                $right_sizer->Show(5, $_[0]); 
 #                $self->Layout
 #            }
-            if ($scrolled_window_sizer->IsShown(2) != $_[0]) {
+            if ($info_sizer->IsShown(2) != $_[0]) {
                 Slic3r::GUI::set_show_print_info($_[0]);
                 return if (wxTheApp->{app_config}->get("view_mode") eq "simple");
-                $scrolled_window_sizer->Show(2, $_[0]); 
-                $scrolled_window_panel->Layout
+                $info_sizer->Show(2, $_[0]); 
+                $self->{right_panel}->Layout
             }
         };
         # Show the box initially, let it be shown after the slicing is finished.
         $self->{"print_info_box_show"}->(0);
 
-        $self->{right_panel}->SetSizer($right_sizer);
-
         my $hsizer = Wx::BoxSizer->new(wxHORIZONTAL);
         $hsizer->Add($self->{preview_notebook}, 1, wxEXPAND | wxTOP, 1);
         $hsizer->Add($self->{right_panel}, 0, wxEXPAND | wxLEFT | wxRIGHT, 3);
@@ -558,7 +552,7 @@ sub new {
         Slic3r::GUI::set_objects_from_perl( $self->{right_panel},
                                 $frequently_changed_parameters_sizer,
                                 $expert_mode_part_sizer,
-                                $scrolled_window_sizer,
+                                $info_sizer,
                                 $self->{btn_export_gcode},
                                 $self->{btn_export_stl},
                                 $self->{btn_reslice},
diff --git a/xs/src/slic3r/GUI/GUI.cpp b/xs/src/slic3r/GUI/GUI.cpp
index bbb113105f..1700512079 100644
--- a/xs/src/slic3r/GUI/GUI.cpp
+++ b/xs/src/slic3r/GUI/GUI.cpp
@@ -142,10 +142,11 @@ wxDataViewCtrl *m_objects_ctrl = nullptr;
 PrusaCollapsiblePane	*m_collpane_settings = nullptr;
 
 wxFont		g_small_font{ wxSystemSettings::GetFont(wxSYS_DEFAULT_GUI_FONT) };
-#ifdef __WXMAC__
-g_small_font->SetPointSize(11);
-#endif /*__WXMAC__*/
 wxFont		g_bold_font{ wxSystemSettings::GetFont(wxSYS_DEFAULT_GUI_FONT).Bold() };
+#ifdef __WXMAC__
+g_small_font.SetPointSize(11);
+g_bold_font.SetPointSize(11);
+#endif /*__WXMAC__*/
 
 static void init_label_colours()
 {
@@ -833,7 +834,6 @@ wxString from_u8(const std::string &str)
 PrusaCollapsiblePane* add_prusa_collapsible_pane(wxWindow* parent, wxBoxSizer* sizer_parent, const wxString& name, std::function<wxSizer *(wxWindow *)> content_function)
 {
 	auto *collpane = new PrusaCollapsiblePane(parent, wxID_ANY, name);
-	collpane->SetTopParent(g_right_panel);
 	// add the pane with a zero proportion value to the sizer which contains it
 	sizer_parent->Add(collpane, 0, wxGROW | wxALL, 0);
 
@@ -844,14 +844,14 @@ PrusaCollapsiblePane* add_prusa_collapsible_pane(wxWindow* parent, wxBoxSizer* s
 	wxSizer *sizer_pane = new wxBoxSizer(wxVERTICAL);
 	sizer_pane->Add(sizer, 1, wxGROW | wxEXPAND | wxBOTTOM, 2);
 	win->SetSizer(sizer_pane);
-	sizer_pane->SetSizeHints(win);
+// 	sizer_pane->SetSizeHints(win);
 	return collpane;
 }
 
 wxBoxSizer* content_objects_list(wxWindow *win)
 {
 	m_objects_ctrl = new wxDataViewCtrl(win, wxID_ANY, wxDefaultPosition, wxDefaultSize);
-	m_objects_ctrl->SetBestFittingSize(wxSize(-1, 150)); // TODO - Set correct height according to the opened/closed objects
+	m_objects_ctrl->SetInitialSize(wxSize(-1, 150)); // TODO - Set correct height according to the opened/closed objects
 	auto objects_sz = new wxBoxSizer(wxVERTICAL);
 	objects_sz->Add(m_objects_ctrl, 1, wxGROW | wxLEFT/*ALL*/, 20/*5*/);
 
@@ -883,18 +883,17 @@ wxBoxSizer* content_objects_list(wxWindow *win)
 		wxDATAVIEW_COL_SORTABLE | wxDATAVIEW_COL_RESIZABLE);
 	m_objects_ctrl->AppendColumn(column02);
 
-	m_objects_ctrl->Bind(wxEVT_DATAVIEW_SELECTION_CHANGED, [objects_model](wxCommandEvent& evt)
+	m_objects_ctrl->Bind(wxEVT_DATAVIEW_SELECTION_CHANGED, [objects_model](wxEvent& evt)
 	{
 		wxWindowUpdateLocker noUpdates(g_right_panel);
 		auto item = m_objects_ctrl->GetSelection();
 		if (!item) return;
+//		m_objects_ctrl->SetSize(m_objects_ctrl->GetBestSize()); // TODO override GetBestSize(), than use it
 		auto show_obj_sizer = objects_model->GetParent(item) == wxDataViewItem(0);
 		m_sizer_object_buttons->Show(show_obj_sizer);
 		m_sizer_part_buttons->Show(!show_obj_sizer);
 		m_collpane_settings->SetLabelText((show_obj_sizer ? _(L("Object Settings")) : _(L("Part Settings"))) + ":");
-		m_collpane_settings->Show(true);
-
-		g_right_panel->Layout();
+		m_collpane_settings->show_it(true);
 	});
 
 	return objects_sz;
@@ -921,15 +920,13 @@ wxBoxSizer* content_edit_object_buttons(wxWindow* win)
     btn_move_up->SetBitmap(wxBitmap(from_u8(Slic3r::var("bullet_arrow_up.png")), wxBITMAP_TYPE_PNG));
     btn_move_down->SetBitmap(wxBitmap(from_u8(Slic3r::var("bullet_arrow_down.png")), wxBITMAP_TYPE_PNG));
 
-	m_sizer_object_buttons = new /*wxFlex*/wxGridSizer(1, 3, 0, 0);
-// 	static_cast<wxFlexGridSizer*>(m_sizer_object_buttons)->SetFlexibleDirection(wxBOTH);
+	m_sizer_object_buttons = new wxGridSizer(1, 3, 0, 0);
 	m_sizer_object_buttons->Add(btn_load_part, 0, wxEXPAND);
 	m_sizer_object_buttons->Add(btn_load_modifier, 0, wxEXPAND);
 	m_sizer_object_buttons->Add(btn_load_lambda_modifier, 0, wxEXPAND);
 	m_sizer_object_buttons->Show(false);
 
-	m_sizer_part_buttons = new /*wxFlex*/wxGridSizer(1, 3, 0, 0);
-//	m_sizer_part_buttons->SetFlexibleDirection(wxBOTH);
+	m_sizer_part_buttons = new wxGridSizer(1, 3, 0, 0);
 	m_sizer_part_buttons->Add(btn_delete, 0, wxEXPAND);
 	m_sizer_part_buttons->Add(btn_split, 0, wxEXPAND);
 	{
@@ -948,8 +945,8 @@ wxBoxSizer* content_edit_object_buttons(wxWindow* win)
 	btn_move_up->SetFont(Slic3r::GUI::small_font());
 	btn_move_down->SetFont(Slic3r::GUI::small_font());
 
-	sizer->Add(m_sizer_object_buttons, 0, wxEXPAND|wxLEFT, 20/*wxALIGN_CENTER_HORIZONTAL*/);
-	sizer->Add(m_sizer_part_buttons, 0, wxEXPAND|wxLEFT, 20/*wxALIGN_CENTER_HORIZONTAL*/);
+	sizer->Add(m_sizer_object_buttons, 0, wxEXPAND|wxLEFT, 20);
+	sizer->Add(m_sizer_part_buttons, 0, wxEXPAND|wxLEFT, 20);
 	return sizer;
 }
 
@@ -1021,31 +1018,29 @@ wxBoxSizer* content_settings(wxWindow *win)
 
 void add_expert_mode_part(wxWindow* parent, wxBoxSizer* sizer)
 {
-	auto main_sizer = new wxBoxSizer(wxVERTICAL);
-	auto main_page = new wxPanel(parent, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
-	main_page->SetSizer(main_sizer);
-	sizer->Add(main_page, 1, wxEXPAND | wxALL, 1);
+	wxWindowUpdateLocker noUpdates(parent);
 
 	// Experiments with new UI
 
 	// *** Objects List ***	
- 	auto collpane = add_prusa_collapsible_pane(main_page, main_sizer, "Objects List:", content_objects_list);
-	collpane->Bind(wxEVT_COLLAPSIBLEPANE_CHANGED, ([collpane](wxCommandEvent e){
+ 	auto collpane = add_prusa_collapsible_pane(parent, sizer, "Objects List:", content_objects_list);
+	collpane->Bind(wxEVT_COLLAPSIBLEPANE_CHANGED, ([collpane](wxCommandEvent& e){
+		e.Skip();
 		wxWindowUpdateLocker noUpdates(g_right_panel);
 		if (collpane->IsCollapsed()) {
 			m_sizer_object_buttons->Show(false);
 			m_sizer_part_buttons->Show(false);
-			m_collpane_settings->Show(false);
+			m_collpane_settings->show_it(false);
 		}
 		else 
 			m_objects_ctrl->UnselectAll();
+		
 		g_right_panel->Layout();
 	}));
 
 	// *** Object/Part Settings ***
-	m_collpane_settings = add_prusa_collapsible_pane(main_page, main_sizer, "Settings:", content_settings);
-	m_collpane_settings->Show(false);
-
+	m_collpane_settings = add_prusa_collapsible_pane(parent, sizer, "Settings:", content_settings);
+	m_collpane_settings->Hide(); // ? TODO why doesn't work?
 
 	// More experiments with UI
 // 	auto listctrl = new wxDataViewListCtrl(main_page, wxID_ANY, wxDefaultPosition, wxSize(-1, 100));
diff --git a/xs/src/slic3r/GUI/wxExtensions.cpp b/xs/src/slic3r/GUI/wxExtensions.cpp
index d993b22403..eb851ffd47 100644
--- a/xs/src/slic3r/GUI/wxExtensions.cpp
+++ b/xs/src/slic3r/GUI/wxExtensions.cpp
@@ -257,6 +257,36 @@ void PrusaCollapsiblePane::UpdateBtnBmp()
 	Layout();
 }
 
+void PrusaCollapsiblePane::OnStateChange_(const wxSize& sz)
+{
+	SetSize(sz);
+
+	if (this->HasFlag(wxCP_NO_TLW_RESIZE))
+	{
+		// the user asked to explicitly handle the resizing itself...
+		return;
+	}
+
+	auto top = GetParent(); //right_panel
+	if (!top)
+		return;
+
+	wxSizer *sizer = top->GetSizer();
+	if (!sizer)
+		return;
+
+	const wxSize newBestSize = sizer->ComputeFittingClientSize(top);
+	top->SetMinClientSize(newBestSize);
+
+ 	wxWindowUpdateLocker noUpdates_p(top->GetParent());
+	// we shouldn't attempt to resize a maximized window, whatever happens
+// 	if (!top->IsMaximized())
+// 		top->SetClientSize(newBestSize);
+		top->GetParent()->Layout();
+		top->Refresh();
+}
+
+
 void PrusaCollapsiblePane::Collapse(bool collapse)
 {
 	// optimization
@@ -268,10 +298,20 @@ void PrusaCollapsiblePane::Collapse(bool collapse)
 	// update our state
 	m_pPane->Show(!collapse);
 
+	// update button label
+#if defined( __WXMAC__ ) && !defined(__WXUNIVERSAL__)
+	m_pButton->SetOpen(!collapse);
+#else 
+#ifdef __WXMSW__
 	// update button bitmap
 	UpdateBtnBmp();
+#else
+	// NB: this must be done after updating our "state"
+	m_pButton->SetLabel(GetBtnLabel());
+#endif //__WXMSW__
+#endif
 
-	OnStateChange(GetBestSize());
+	OnStateChange_(GetBestSize());
 }
 
 void PrusaCollapsiblePane::SetLabel(const wxString &label)
diff --git a/xs/src/slic3r/GUI/wxExtensions.hpp b/xs/src/slic3r/GUI/wxExtensions.hpp
index b256ac8bbe..51c77210e4 100644
--- a/xs/src/slic3r/GUI/wxExtensions.hpp
+++ b/xs/src/slic3r/GUI/wxExtensions.hpp
@@ -84,7 +84,6 @@ class PrusaCollapsiblePane : public wxCollapsiblePane
 	wxBitmap	m_bmp_close;
 	wxBitmap	m_bmp_open;
 #endif //__WXMSW__
-	wxWindow*	m_top_parent = nullptr;
 public:
 	PrusaCollapsiblePane() {}
 	PrusaCollapsiblePane(	wxWindow *parent,
@@ -101,35 +100,10 @@ public:
 #else
 		Create(parent, winid, label);
 #endif //__WXMSW__
-		this->Bind(wxEVT_COLLAPSIBLEPANE_CHANGED, ([parent, this](wxCommandEvent e){
-			wxWindowUpdateLocker noUpdates_cp(this);
-			wxWindowUpdateLocker noUpdates(parent);
-
-			parent->Layout();
-			this->Refresh();
-
-			if (m_top_parent)
-			{
-				m_top_parent->GetSizer()->Layout();
-			}
-			else{
- 				wxGetTopLevelParent(this)->Layout();
-			}
-			
-// 			if (parent->GetParent()){
-// 				parent->GetParent()->Layout();
-// 				parent->Refresh();
-// 			}
-// 			else{
-//  			parent->Layout();
-//  			this->Refresh();}
-		}));
 	}
 
 	~PrusaCollapsiblePane() {}
 
-	void SetTopParent(wxWindow *parent) { m_top_parent = parent; }
-
 #ifdef __WXMSW__
 	bool Create(wxWindow *parent,
 				wxWindowID id,
@@ -141,11 +115,12 @@ public:
 				const wxString& name);
 
 	void UpdateBtnBmp();
-	void Collapse(bool collapse) override;
 	void SetLabel(const wxString &label) override;
 	bool Layout() override;
 #endif //__WXMSW__
-
+	void Collapse(bool collapse) override;
+	void OnStateChange_(const wxSize& sz); //override of OnStateChange
+	void show_it(bool show) { Show(show); OnStateChange_(GetBestSize()); }
 };